What is a change of plane? It’s the edge where two sides of an object meet. Sometimes this is very easy to see. Take a look at this box, for example. Each side of the box is a plane and you can easily see them meet. So it’s really easy to do a line drawing of the box by simply drawing all the edges. Remember this idea of ‘change of plane’ because it’s an important one that will help your drawing.
Finding the Plane Changes
When the change of plane happens against the background, it’s easy - that outline is clear and sharp. But what about the edges between two planes facing us? They form a gradual curve. Sometimes we can make a ‘best guess’ as to where the middle of the change of plane is. We can also draw as close to the edge of each plane as we can, leaving the curved area between them. Sometimes this can work quite well and the somewhat visible edges on the face of the dice mean you can get away with a solid line in this case. However, it does make the edge look much harder than it really is.
Using Implied Line
The other option is to draw using implied line. An implied line uses a slight break in the line to suggest that an edge is there, but it isn’t as strong as other lines in the drawing. If varied line weight is being used, we can lift the pencil off and then on again gradually, or we can use a clean break or a dotted line. The brain interprets these broken lines as being less sharp or hard than the solid lines. This can help you create the effect of the gradual change of plane. The die on the right is drawn this way, with broken lines suggesting the more subtle curved edges. The human face is a favorite subject and it has many complex and subtle changes of plane. Let’s take a look at this store mannequin as a slightly simplified example. With a bit of imagination, we can visualize some planes in the face:
The sides of the face and jaw.The forehead, nose, top of the cheeks and chin as the forward planes.The lips are tilted and the top of the head is a horizontal plane.
Of course, you can break the planes down much smaller. Studying the planes of the face in this way can be a useful exercise and this is an approach we’ll revisit in a shading exercise. But for line drawing, we really need to ignore most of these planes otherwise our subject will look more robot than human. Tip: If you can visit an art gallery or museum, try drawing a portrait sculpture and breaking down the planes of the face. The white marble of a sculpture, without the confusing detail of real skin, makes a good subject. When portrait drawing with pure contour, we almost always ignore many of the subtle planes of the face. However, even quite strong changes of plane, such as along the side of the nose, need to be toned down at times depending on the angle of the face. As you can see in this example, clearly defining that edge doesn’t work in this case. Another problem with portrait drawing is a change of pigment: the girl’s lips are pink, but the changes of the plane around the mouth are very subtle. Outlining them like this can make them look like paper cut-outs. You’ll often see manga illustrations that use a small line under the lip or nose or across the cheek to suggest a plane without too much detail. In this example, only the very strongest changes of plane are outlined. Broken or implied line is then used for the softer changes of plane. Deciding where to put the implied line is fairly easy with the side of the nose and the shape of the mouth. It’s trickier with the very gradual changes across a rounded cheek or chin. Sometimes in these areas, a couple of short marks will just suggest the contour every so slightly. So as you can see, implied line, in conjunction with an awareness of change of plane, can help you create a more natural and three-dimensional look in your line drawings.
